Merge pull request #159 from puppetlabs/dont-call-statsd-a-comeback

[QENG-4075] Land statsd support after earlier ci.next changes

Gemfile

@@ -12,10 +12,12 @@ gem 'rbvmomi', '>= 1.8'
 gem 'redis', '>= 3.2'
 gem 'sinatra', '>= 1.4'
 gem 'net-ldap', '<= 0.12.1' # keep compatibility w/ jruby & mri-1.9.3
+gem 'statsd-ruby', '>= 1.3.0', :require => 'statsd'
 
 # Test deps
 group :test do
   gem 'rack-test', '>= 0.6'
   gem 'rspec', '>= 3.2'
+  gem 'simplecov', '>= 0.11.2'
   gem 'yarjuf', '>= 2.0'
 end

lib/vmpooler.rb

@@ -12,7 +12,7 @@ module Vmpooler
   require 'yaml'
   require 'set'
 
-  %w( api graphite logger pool_manager vsphere_helper ).each do |lib|
+  %w( api graphite logger pool_manager vsphere_helper statsd dummy_statsd ).each do |lib|
     begin
       require "vmpooler/#{lib}"
     rescue LoadError
@@ -53,10 +53,6 @@ module Vmpooler
       end
     end
 
-    if parsed_config[:graphite]['server']
-      parsed_config[:graphite]['prefix'] ||= 'vmpooler'
-    end
-
     if parsed_config[:tagfilter]
       parsed_config[:tagfilter].keys.each do |tag|
         parsed_config[:tagfilter][tag] = Regexp.new(parsed_config[:tagfilter][tag])
@@ -64,7 +60,6 @@ module Vmpooler
     end
 
     parsed_config[:uptime] = Time.now
-
     parsed_config
   end
 
@@ -76,11 +71,13 @@ module Vmpooler
     Vmpooler::Logger.new logfile
   end
 
-  def self.new_graphite(server)
+  def self.new_metrics(params)
-    if server.nil? or server.empty? or server.length == 0
+    if params[:statsd]
-      nil
+      Vmpooler::Statsd.new(params[:statsd])
+    elsif params[:graphite]
+      Vmpooler::Graphite.new(params[:graphite])
     else
-      Vmpooler::Graphite.new server
+      Vmpooler::DummyStatsd.new
     end
   end
 

lib/vmpooler/api.rb

@@ -42,9 +42,10 @@ module Vmpooler
     use Vmpooler::API::Reroute
     use Vmpooler::API::V1
 
-    def configure(config, redis, environment = :production)
+    def configure(config, redis, metrics, environment = :production)
       self.settings.set :config, config
       self.settings.set :redis, redis
+      self.settings.set :metrics, metrics
       self.settings.set :environment, environment
     end
 

lib/vmpooler/api/dashboard.rb

@@ -1,9 +1,57 @@
 module Vmpooler
   class API
   class Dashboard < Sinatra::Base
+
+    # handle to the App's configuration information
+    def config
+      @config ||= Vmpooler::API.settings.config
+    end
+
+    # configuration setting for server hosting graph URLs to view
+    def graph_server
+      return @graph_server if @graph_server
+
+      if config[:graphs]
+        return false unless config[:graphs]['server']
+        @graph_server = config[:graphs]['server']
+      elsif config[:graphite]
+        return false unless config[:graphite]['server']
+        @graph_server = config[:graphite]['server']
+      else
+        false
+      end
+    end
+
+    # configuration setting for URL prefix for graphs to view
+    def graph_prefix
+      return @graph_prefix if @graph_prefix
+
+      if config[:graphs]
+        return "vmpooler" unless config[:graphs]['prefix']
+        @graph_prefix = config[:graphs]['prefix']
+      elsif config[:graphite]
+        return false unless config[:graphite]['prefix']
+        @graph_prefix = config[:graphite]['prefix']
+      else
+        false
+      end
+    end
+
+    # what is the base URL for viewable graphs?
+    def graph_url
+      return false unless graph_server && graph_prefix
+      @graph_url ||= "http://#{graph_server}/render?target=#{graph_prefix}"
+    end
+
+    # return a full URL to a viewable graph for a given metrics target (graphite syntax)
+    def graph_link(target = "")
+      return "" unless graph_url
+      graph_url + target
+    end
+
+
     get '/dashboard/stats/vmpooler/pool/?' do
       content_type :json
-
       result = {}
 
       Vmpooler::API.settings.config[:pools].each do |pool|
@@ -13,13 +61,11 @@ module Vmpooler
       end
 
       if params[:history]
-        if Vmpooler::API.settings.config[:graphite]['server']
+        if graph_url
           history ||= {}
 
           begin
-            buffer = open(
+            buffer = open(graph_link('.ready.*&from=-1hour&format=json')).read
-              'http://' + Vmpooler::API.settings.config[:graphite]['server'] + '/render?target=' + Vmpooler::API.settings.config[:graphite]['prefix'] + '.ready.*&from=-1hour&format=json'
-            ).read
             history = JSON.parse(buffer)
 
             history.each do |pool|
@@ -52,59 +98,47 @@ module Vmpooler
           end
         end
       end
-
       JSON.pretty_generate(result)
     end
 
     get '/dashboard/stats/vmpooler/running/?' do
       content_type :json
-
       result = {}
 
       Vmpooler::API.settings.config[:pools].each do |pool|
         running = Vmpooler::API.settings.redis.scard('vmpooler__running__' + pool['name'])
         pool['major'] = Regexp.last_match[1] if pool['name'] =~ /^(\w+)\-/
-
         result[pool['major']] ||= {}
-
         result[pool['major']]['running'] = result[pool['major']]['running'].to_i + running.to_i
       end
 
       if params[:history]
-        if Vmpooler::API.settings.config[:graphite]['server']
+        if graph_url
           begin
-            buffer = open(
+            buffer = open(graph_link('.running.*&from=-1hour&format=json')).read
-              'http://' + Vmpooler::API.settings.config[:graphite]['server'] + '/render?target=' + Vmpooler::API.settings.config[:graphite]['prefix'] + '.running.*&from=-1hour&format=json'
-            ).read
             JSON.parse(buffer).each do |pool|
               if pool['target'] =~ /.*\.(.*)$/
                 pool['name'] = Regexp.last_match[1]
-
                 pool['major'] = Regexp.last_match[1] if pool['name'] =~ /^(\w+)\-/
-
                 result[pool['major']]['history'] ||= Array.new
 
                 for i in 0..pool['datapoints'].length
                   if
                     pool['datapoints'][i] &&
                     pool['datapoints'][i][0]
-
                     pool['last'] = pool['datapoints'][i][0]
-
                     result[pool['major']]['history'][i] ||= 0
                     result[pool['major']]['history'][i] = result[pool['major']]['history'][i].to_i + pool['datapoints'][i][0].to_i
                   else
                     result[pool['major']]['history'][i] = result[pool['major']]['history'][i].to_i + pool['last'].to_i
                   end
                 end
-
               end
             end
           rescue
           end
         end
       end
-
       JSON.pretty_generate(result)
     end
   end

lib/vmpooler/api/v1.rb

@@ -12,6 +12,10 @@ module Vmpooler
       Vmpooler::API.settings.redis
     end
 
+    def metrics
+      Vmpooler::API.settings.metrics
+    end
+
     def config
       Vmpooler::API.settings.config[:config]
     end
@@ -34,13 +38,11 @@ module Vmpooler
 
     def fetch_single_vm(template)
       vm = backend.spop('vmpooler__ready__' + template)
-
       return [vm, template] if vm
 
       aliases = Vmpooler::API.settings.config[:alias]
       if aliases && aliased_template = aliases[template]
         vm = backend.spop('vmpooler__ready__' + aliased_template)
-
         return [vm, aliased_template] if vm
       end
 
@@ -85,14 +87,16 @@ module Vmpooler
       failed = false
       vms = []
 
-      payload.each do |template, count|
+      payload.each do |requested, count|
         count.to_i.times do |_i|
-          vm, name = fetch_single_vm(template)
+          vm, name = fetch_single_vm(requested)
           if !vm
             failed = true
+            metrics.increment('checkout.empty.' + requested)
             break
           else
             vms << [ name, vm ]
+            metrics.increment('checkout.success.' + name)
           end
         end
       end
@@ -372,9 +376,18 @@ module Vmpooler
 
       payload = JSON.parse(request.body.read)
 
-      if all_templates_valid?(payload)
+      if payload
+        invalid = invalid_templates(payload)
+        if invalid.empty?
           result = atomically_allocate_vms(payload)
         else
+          invalid.each do |bad_template|
+            metrics.increment('checkout.invalid.' + bad_template)
+          end
+          status 404
+        end
+      else
+        metrics.increment('checkout.invalid.unknown')
         status 404
       end
 
@@ -392,12 +405,12 @@ module Vmpooler
       payload
     end
 
-    def all_templates_valid?(payload)
+    def invalid_templates(payload)
-      return false unless payload
+      invalid = []
-
+      payload.keys.each do |template|
-      payload.keys.all? do |templates|
+        invalid << template unless pool_exists?(template)
-        pool_exists?(templates)
       end
+      invalid
     end
 
     post "#{api_prefix}/vm/:template/?" do
@@ -406,9 +419,18 @@ module Vmpooler
 
       payload = extract_templates_from_query_params(params[:template])
 
-      if all_templates_valid?(payload)
+      if payload
+        invalid = invalid_templates(payload)
+        if invalid.empty?
           result = atomically_allocate_vms(payload)
         else
+          invalid.each do |bad_template|
+            metrics.increment('checkout.invalid.' + bad_template)
+          end
+          status 404
+        end
+      else
+        metrics.increment('checkout.invalid.unknown')
         status 404
       end
 

lib/vmpooler/dummy_statsd.rb

@@ -0,0 +1,20 @@
+module Vmpooler
+  class DummyStatsd
+    attr_reader :server, :port, :prefix
+
+    def initialize(params = {})
+    end
+
+    def increment(label)
+      true
+    end
+
+    def gauge(label, value)
+      true
+    end
+
+    def timing(label, duration)
+      true
+    end
+  end
+end

lib/vmpooler/graphite.rb

@@ -2,18 +2,41 @@ require 'rubygems' unless defined?(Gem)
 
 module Vmpooler
   class Graphite
-    def initialize(
+    attr_reader :server, :port, :prefix
-      s = 'graphite'
+
-    )
+    def initialize(params = {})
-      @server = s
+      if params["server"].nil? || params["server"].empty?
+        raise ArgumentError, "Graphite server is required. Config: #{params.inspect}"
+      end
+
+      @server = params["server"]
+      @port   = params["port"]   || 2003
+      @prefix = params["prefix"] || "vmpooler"
+    end
+
+    def increment(label)
+      log label, 1
+    end
+
+    def gauge(label, value)
+      log label, value
+    end
+
+    def timing(label, duration)
+      log label, duration
     end
 
     def log(path, value)
       Thread.new do
-        socket = TCPSocket.new(@server, 2003)
+        socket = TCPSocket.new(server, port)
-        socket.puts "#{path} #{value} #{Time.now.to_i}"
+        begin
+          socket.puts "#{prefix}.#{path} #{value} #{Time.now.to_i}"
+        ensure
           socket.close
         end
       end
+    rescue => err
+      $stderr.puts "Failure logging #{path} to graphite server [#{server}:#{port}]: #{err}"
+    end
   end
 end

lib/vmpooler/pool_manager.rb

@@ -1,14 +1,13 @@
 module Vmpooler
   class PoolManager
-    def initialize(config, logger, redis, graphite=nil)
+    def initialize(config, logger, redis, metrics)
       $config = config
 
       # Load logger library
       $logger = logger
 
-      unless graphite.nil?
+      # metrics logging handle
-        $graphite = graphite
+      $metrics = metrics
-      end
 
       # Connect to Redis
       $redis = redis
@@ -63,7 +62,7 @@ module Vmpooler
           (host.summary.guest.hostName == vm)
 
         begin
-          Socket.getaddrinfo(vm, nil)
+          Socket.getaddrinfo(vm, nil)  # WTF?
         rescue
         end
 
@@ -257,10 +256,7 @@ module Vmpooler
 
         $redis.decr('vmpooler__tasks__clone')
 
-        begin
+        $metrics.timing("clone.#{vm['template']}", finish)
-          $graphite.log($config[:graphite]['prefix'] + ".clone.#{vm['template']}", finish) if defined? $graphite
-        rescue
-        end
       end
     end
 
@@ -293,8 +289,7 @@ module Vmpooler
           finish = '%.2f' % (Time.now - start)
 
           $logger.log('s', "[-] [#{pool}] '#{vm}' destroyed in #{finish} seconds")
-
+          $metrics.timing("destroy.#{pool}", finish)
-          $graphite.log($config[:graphite]['prefix'] + ".destroy.#{pool}", finish) if defined? $graphite
         end
       end
     end
@@ -564,13 +559,8 @@ module Vmpooler
       ready = $redis.scard('vmpooler__ready__' + pool['name'])
       total = $redis.scard('vmpooler__pending__' + pool['name']) + ready
 
-      begin
+      $metrics.gauge('ready.' + pool['name'], $redis.scard('vmpooler__ready__' + pool['name']))
-        if defined? $graphite
+      $metrics.gauge('running.' + pool['name'], $redis.scard('vmpooler__running__' + pool['name']))
-          $graphite.log($config[:graphite]['prefix'] + '.ready.' + pool['name'], $redis.scard('vmpooler__ready__' + pool['name']))
-          $graphite.log($config[:graphite]['prefix'] + '.running.' + pool['name'], $redis.scard('vmpooler__running__' + pool['name']))
-        end
-      rescue
-      end
 
       if $redis.get('vmpooler__empty__' + pool['name'])
         unless ready == 0

lib/vmpooler/statsd.rb

@@ -0,0 +1,37 @@
+require 'rubygems' unless defined?(Gem)
+require 'statsd'
+
+module Vmpooler
+  class Statsd
+    attr_reader :server, :port, :prefix
+
+    def initialize(params = {})
+      if params["server"].nil? || params["server"].empty?
+        raise ArgumentError, "Statsd server is required. Config: #{params.inspect}"
+      end
+
+      host    = params["server"]
+      @port    = params["port"]   || 8125
+      @prefix = params["prefix"] || 'vmpooler'
+      @server = ::Statsd.new(host, @port)
+    end
+
+    def increment(label)
+      server.increment(prefix + "." + label)
+    rescue => err
+      $stderr.puts "Failure incrementing #{prefix}.#{label} on statsd server [#{server}:#{port}]: #{err}"
+    end
+
+    def gauge(label, value)
+      server.gauge(prefix + "." + label, value)
+    rescue => err
+      $stderr.puts "Failure updating gauge #{prefix}.#{label} on statsd server [#{server}:#{port}]: #{err}"
+    end
+
+    def timing(label, duration)
+      server.timing(prefix + "." + label, duration)
+    rescue => err
+      $stderr.puts "Failure updating timing #{prefix}.#{label} on statsd server [#{server}:#{port}]: #{err}"
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,5 +1,10 @@
+require 'simplecov'
+SimpleCov.start do
+  add_filter '/spec/'
+end
 require 'helpers'
 require 'rbvmomi'
 require 'rspec'
 require 'vmpooler'
 require 'redis'
+require 'vmpooler/statsd'

spec/vmpooler/api/v1/vm_spec.rb

@@ -20,7 +20,7 @@ describe Vmpooler::API::V1 do
 
   describe '/vm' do
     let(:prefix) { '/api/v1' }
-
+    let(:metrics) { Vmpooler::DummyStatsd.new }
     let(:config) {
       {
         config: {
@@ -31,6 +31,7 @@ describe Vmpooler::API::V1 do
           {'name' => 'pool1', 'size' => 5},
           {'name' => 'pool2', 'size' => 10}
         ],
+        statsd: { 'prefix' => 'stats_prefix'},
         alias: { 'poolone' => 'pool1' },
         pool_names: [ 'pool1', 'pool2', 'poolone' ]
       }
@@ -43,6 +44,7 @@ describe Vmpooler::API::V1 do
 
       app.settings.set :config, config
       app.settings.set :redis, redis
+      app.settings.set :metrics, metrics
       app.settings.set :config, auth: false
       create_token('abcdefghijklmnopqrstuvwxyz012345', 'jdoe', current_time)
     end

spec/vmpooler/api/v1/vm_template_spec.rb

@@ -20,7 +20,7 @@ describe Vmpooler::API::V1 do
 
   describe '/vm/:template' do
     let(:prefix) { '/api/v1' }
-
+    let(:metrics) { Vmpooler::DummyStatsd.new }
     let(:config) {
       {
         config: {
@@ -31,6 +31,7 @@ describe Vmpooler::API::V1 do
           {'name' => 'pool1', 'size' => 5},
           {'name' => 'pool2', 'size' => 10}
         ],
+        statsd: { 'prefix' => 'stats_prefix'},
         alias: { 'poolone' => 'pool1' },
         pool_names: [ 'pool1', 'pool2', 'poolone' ]
       }
@@ -43,6 +44,7 @@ describe Vmpooler::API::V1 do
 
       app.settings.set :config, config
       app.settings.set :redis, redis
+      app.settings.set :metrics, metrics
       app.settings.set :config, auth: false
       create_token('abcdefghijklmnopqrstuvwxyz012345', 'jdoe', current_time)
     end

spec/vmpooler/pool_manager_spec.rb

@@ -4,14 +4,14 @@ require 'time'
 describe 'Pool Manager' do
   let(:logger) { double('logger') }
   let(:redis) { double('redis') }
+  let(:metrics) { Vmpooler::DummyStatsd.new }
   let(:config) { {} }
-  let(:graphite) { nil }
   let(:pool) { 'pool1' }
   let(:vm) { 'vm1' }
   let(:timeout) { 5 }
   let(:host) { double('host') }
 
-  subject { Vmpooler::PoolManager.new(config, logger, redis, graphite) }
+  subject { Vmpooler::PoolManager.new(config, logger, redis, metrics) }
 
   describe '#_check_pending_vm' do
     let(:pool_helper) { double('pool') }
@@ -23,14 +23,12 @@ describe 'Pool Manager' do
     end
 
     context 'host not in pool' do
-
       it 'calls fail_pending_vm' do
         allow(pool_helper).to receive(:find_vm).and_return(nil)
         allow(redis).to receive(:hget)
         expect(redis).to receive(:hget).with(String, 'clone').once
         subject._check_pending_vm(vm, pool, timeout)
       end
-
     end
 
     context 'host is in pool' do
@@ -58,7 +56,6 @@ describe 'Pool Manager' do
     end
 
     context 'a host without correct summary' do
-
       it 'does nothing when summary is nil' do
         allow(host).to receive(:summary).and_return nil
         subject.move_pending_vm_to_ready(vm, pool, host)
@@ -114,7 +111,6 @@ describe 'Pool Manager' do
 
         subject.move_pending_vm_to_ready(vm, pool, host)
       end
-
     end
   end
 
@@ -191,9 +187,7 @@ describe 'Pool Manager' do
 
         subject._check_running_vm(vm, pool, timeout)
       end
-
     end
-
   end
 
   describe '#move_running_to_completed' do
@@ -240,15 +234,62 @@ describe 'Pool Manager' do
     end
 
     context 'logging' do
-
       it 'logs empty pool' do
         allow(redis).to receive(:scard).with('vmpooler__pending__pool1').and_return(0)
         allow(redis).to receive(:scard).with('vmpooler__ready__pool1').and_return(0)
+        allow(redis).to receive(:scard).with('vmpooler__running__pool1').and_return(0)
 
         expect(logger).to receive(:log).with('s', "[!] [pool1] is empty")
         subject._check_pool(config[:pools][0])
       end
+    end
+  end
 
+  describe '#_stats_running_ready' do
+    let(:pool_helper) { double('pool') }
+    let(:vsphere) { {pool => pool_helper} }
+    let(:metrics) { Vmpooler::DummyStatsd.new }
+    let(:config) { {
+      config: { task_limit: 10 },
+      pools: [ {'name' => 'pool1', 'size' => 5} ],
+      graphite: { 'prefix' => 'vmpooler' }
+    } }
+
+    before do
+      expect(subject).not_to be_nil
+      $vsphere = vsphere
+      allow(logger).to receive(:log)
+      allow(pool_helper).to receive(:find_folder)
+      allow(redis).to receive(:smembers).and_return([])
+      allow(redis).to receive(:set)
+      allow(redis).to receive(:get).with('vmpooler__tasks__clone').and_return(0)
+      allow(redis).to receive(:get).with('vmpooler__empty__pool1').and_return(nil)
+    end
+
+    context 'metrics' do
+      subject { Vmpooler::PoolManager.new(config, logger, redis, metrics) }
+
+      it 'increments metrics' do
+        allow(redis).to receive(:scard).with('vmpooler__ready__pool1').and_return(1)
+        allow(redis).to receive(:scard).with('vmpooler__cloning__pool1').and_return(0)
+        allow(redis).to receive(:scard).with('vmpooler__pending__pool1').and_return(0)
+        allow(redis).to receive(:scard).with('vmpooler__running__pool1').and_return(5)
+
+        expect(metrics).to receive(:gauge).with('ready.pool1', 1)
+        expect(metrics).to receive(:gauge).with('running.pool1', 5)
+        subject._check_pool(config[:pools][0])
+      end
+
+      it 'increments metrics when ready with 0 when pool empty' do
+        allow(redis).to receive(:scard).with('vmpooler__ready__pool1').and_return(0)
+        allow(redis).to receive(:scard).with('vmpooler__cloning__pool1').and_return(0)
+        allow(redis).to receive(:scard).with('vmpooler__pending__pool1').and_return(0)
+        allow(redis).to receive(:scard).with('vmpooler__running__pool1').and_return(5)
+
+        expect(metrics).to receive(:gauge).with('ready.pool1', 0)
+        expect(metrics).to receive(:gauge).with('running.pool1', 5)
+        subject._check_pool(config[:pools][0])
+      end
     end
   end
 
@@ -319,5 +360,4 @@ describe 'Pool Manager' do
       subject._check_snapshot_queue
     end
   end
-
 end

vmpooler

@@ -8,11 +8,12 @@ require 'lib/vmpooler'
 config = Vmpooler.config
 redis_host = config[:redis]['server']
 logger_file = config[:config]['logfile']
-graphite = config[:graphite]['server'] ? config[:graphite]['server'] : nil
+
+metrics = Vmpooler.new_metrics(config)
 
 api = Thread.new {
   thr = Vmpooler::API.new
-  thr.helpers.configure(config, Vmpooler.new_redis(redis_host))
+  thr.helpers.configure(config, Vmpooler.new_redis(redis_host), metrics)
   thr.helpers.execute!
 }
 
@@ -21,9 +22,8 @@ manager = Thread.new {
     config,
     Vmpooler.new_logger(logger_file),
     Vmpooler.new_redis(redis_host),
-    Vmpooler.new_graphite(graphite)
+    metrics
   ).execute!
 }
 
 [api, manager].each { |t| t.join }
-

vmpooler.yaml.example

@@ -53,20 +53,79 @@
 :redis:
   server: 'redis.company.com'
 
+
+  # :graphs:
+  #
+  # This section contains the server and prefix information for a graphite-
+  # compatible web front-end where graphs may be viewed. This is used by the
+  # vmpooler dashboard to retrieve statistics and graphs for a given instance.
+  #
+  # NOTE: This is not the endpoint for publishing metrics data. See `graphite:`
+  #       and `statsd:` below.
+  #
+  # NOTE: If `graphs:` is not set, for legacy compatibility, `graphite:` will be
+  #       consulted for `server`/`prefix` information to use in locating a
+  #       graph server for our dashboard.  `graphs:` is recommended over
+  #       `graphite:`
+  #
+  #
+  # Available configuration parameters:
+  #
+  #
+  #   - server
+  #     The FQDN hostname of the statsd daemon.
+  #     (required)
+  #
+  #   - prefix
+  #     The prefix to use while storing statsd data.
+  #     (optional; default: 'vmpooler')
+
+  # :statsd:
+  #
+  # This section contains the connection information required to store
+  # historical data via statsd.  This is mutually exclusive with graphite
+  # and takes precedence.
+  #
+  # Available configuration parameters:
+  #
+  #   - server
+  #     The FQDN hostname of the statsd daemon.
+  #     (required)
+  #
+  #   - prefix
+  #     The prefix to use while storing statsd data.
+  #     (optional; default: 'vmpooler')
+  #
+  #   - port
+  #     The UDP port to communicate with the statsd daemon.
+  #     (optional; default: 8125)
+
+  # Example:
+
+  :statsd:
+    server: 'statsd.company.com'
+    prefix: 'vmpooler'
+    port: 8125
+
 # :graphite:
 #
 # This section contains the connection information required to store
-# historical data in an external Graphite database.
+# historical data in an external Graphite database.  This is mutually exclusive
+# with statsd.
 #
 # Available configuration parameters:
 #
 #   - server
 #     The FQDN hostname of the Graphite server.
-#     (optional)
+#     (required)
 #
 #   - prefix
 #     The prefix to use while storing Graphite data.
 #     (optional; default: 'vmpooler')
+#
+#   - port
+#     The TCP port to communicate with the graphite server.
+#     (optional; default: 2003)
 
 # Example:
 
@@ -246,4 +305,3 @@
     size: 5
     timeout: 15
     ready_ttl: 1440
-